To continue our studies on the means by which ecdysone and juvenile hormone control the development of insects and the mechanism by which brain hormone regulates the synthesis of ecdysone in the prothoracic glands. Receptor proteins for ecdysone and juvenile hormone will be investigated utilizing high specific activity hormones. Finally, the action of ecdysone and juvenile hormone will be examined by critically analyzing the acidic proteins and RNA polymerases of target tissues at critical stages.